Thayer's Gull (thayeri)

(last update: January 22, 2013)

Amar Ayyash (USA)
Mars Muusse (Netherlands)

Californian Gull 1st cycle (1CY), November 09 2008, Nimbus Fish Hatchery, Sacramento County, CA. Picture: Dave Johnson.

Visit: Dave's Flickr photostream.

Obvious bi-coloured bill. Note replaced scapulars and several wing-coverts. Some similarity to Thayer's Gull, but CALIFORNIA GULL (w. N. America) similar in overall size but has longer and narrower wings with long wing projection. Almost all winter birds told readily by sharply bicolored pink-and-black bill (can be mostly dark into early winter), which is also relatively longer with only a slight gonydeal expansion. California has earlier and more extensive PA1 molt (often including wing coverts) and has blacker wingtips; in flight, note California’s all-dark primaries (lacking a distinct pale inner panel) and solidly blackish tail.